Study Finds New Target for Assessing Genes Linked to Autism

The recent discovery by researchers at Duke University of a genetic signature that correlates “strongly” with autism may eventually lead to new approaches to the diagnosis and treatment of autism.

Researchers at Duke’s Medical Center found “higher-than-usual” amounts of gene-regulating molecules — methyl groups — in a region of the genome that is responsible for regulating oxytocin receptor expression in patients who have autism. Oxytocin has an impact on social interaction, according to the researchers, who added that “higher methylation of the oxytocin receptor gene may make a person less sensitive to the hormone.”

"In both blood samples and brain tissue, the methylation status of specific nucleotides in the oxytocin receptor gene is significantly higher in someone with autism, about 70 percent, compared to the control population, where it is about 40 percent,” said co-lead author Simon G. Gregory, PhD, assistant professor in Duke’s Department of Medicine.

The researchers looked at 119 individuals with autism to determine their “genomic rearrangements.” When one participant was found to have a DNA deletion of a region that contained the oxytocin receptor gene, the researchers examined the participant’s family and found that the participant had a brother who also had autism, but did not have the deletion. In addition, his mother had symptoms of obsessive-compulsive disorder, and, although the two conditions are not the same, they do share “the symptoms of intensely repetitive thoughts and behaviors.” The team then examined the genome of the participant’s brother and saw “instances of elevated methylation.” After discovering this, the researchers looked back at “independent collections of blood samples and brain tissue from a repository of specimens, and found consistent differences in OXTR methylation.”

According to Gregory and the research team, the findings may lead to new information about which individuals would respond to treatment with oxytocin. In addition, the results of the study provide new information about social isolation, which can be a large part of the autism disorder.

"We are excited about our findings because they represent one of the few occasions in which a mechanism other than genetic susceptibility or genome instability is implicated in the development of autism," Gregory said. "These results provide a possible explanation of why social isolation forms part of the autism spectrum -- because an autistic individual’s ability to respond to oxytocin may be limited. Oxytocin has been tied to levels of trust and ability to read social cues."

Results of the study were also published in BMC Medicine.